Prof. SIEGEL: I'm virtually sure that it's not going to be a long wait. And the reason is we're no longer at high points in the market. In March, we were down more than 50 percent. And I looked all the way back last hundred years. Once you're down 50 percent, your prospects are very good.

NPR: You're saying that the market dropped by so much over the past year that you're saying, surely, this must have been the bottom back in March.

Prof. SIEGEL: Even in December of 1930, where you were 50 percent down from that all-time high in 1929, your five-year return was more than seven percent after inflation. The world looks different once you're down as much as we have been down.